MDEV-7970: EXPLAIN FORMAT=JSON does not print HAVING

Printing non-trivial HAVING added.

mysql-test/r/analyze_format_json.result

@@ -467,3 +467,116 @@ ANALYZE
   }
 }
 drop table t0, t1;
+#
+# MDEV-7970: EXPLAIN FORMAT=JSON does not print HAVING
+#
+create table t0(a int);
+insert into t0 values (0),(1),(2),(3);
+create table t1(a int);
+insert into t1 select A.a + B.a* 10 + C.a * 100 from t0 A, t0 B, t0 C;
+create table t2 (
+a int, 
+b int, 
+key (a)
+);
+insert into t2 select A.a*1000 + B.a, A.a*1000 + B.a from t0 A, t1 B;
+# normal HAVING
+analyze format=json select a, max(b) as TOP from t2 group by a having TOP > a;
+ANALYZE
+{
+  "query_block": {
+    "select_id": 1,
+    "r_loops": 1,
+    "r_total_time_ms": "REPLACED",
+    "having_condition": "(TOP > a)",
+    "filesort": {
+      "r_loops": 1,
+      "r_total_time_ms": "REPLACED",
+      "r_used_priority_queue": false,
+      "r_output_rows": 0,
+      "r_buffer_size": "5Kb",
+      "temporary_table": {
+        "table": {
+          "table_name": "t2",
+          "access_type": "ALL",
+          "r_loops": 1,
+          "rows": 256,
+          "r_rows": 256,
+          "r_total_time_ms": "REPLACED",
+          "filtered": 100,
+          "r_filtered": 100
+        }
+      }
+    }
+  }
+}
+# HAVING is always TRUE (not printed)
+analyze format=json select a, max(b) as TOP from t2 group by a having 1<>2;
+ANALYZE
+{
+  "query_block": {
+    "select_id": 1,
+    "r_loops": 1,
+    "r_total_time_ms": "REPLACED",
+    "filesort": {
+      "r_loops": 1,
+      "r_total_time_ms": "REPLACED",
+      "r_used_priority_queue": false,
+      "r_output_rows": 256,
+      "r_buffer_size": "5Kb",
+      "temporary_table": {
+        "table": {
+          "table_name": "t2",
+          "access_type": "ALL",
+          "r_loops": 1,
+          "rows": 256,
+          "r_rows": 256,
+          "r_total_time_ms": "REPLACED",
+          "filtered": 100,
+          "r_filtered": 100
+        }
+      }
+    }
+  }
+}
+# HAVING is always FALSE (intercepted by message)
+analyze format=json select a, max(b) as TOP from t2 group by a having 1=2;
+ANALYZE
+{
+  "query_block": {
+    "select_id": 1,
+    "table": {
+      "message": "Impossible HAVING"
+    }
+  }
+}
+# HAVING is absent
+analyze format=json select a, max(b) as TOP from t2 group by a;
+ANALYZE
+{
+  "query_block": {
+    "select_id": 1,
+    "r_loops": 1,
+    "r_total_time_ms": "REPLACED",
+    "filesort": {
+      "r_loops": 1,
+      "r_total_time_ms": "REPLACED",
+      "r_used_priority_queue": false,
+      "r_output_rows": 256,
+      "r_buffer_size": "5Kb",
+      "temporary_table": {
+        "table": {
+          "table_name": "t2",
+          "access_type": "ALL",
+          "r_loops": 1,
+          "rows": 256,
+          "r_rows": 256,
+          "r_total_time_ms": "REPLACED",
+          "filtered": 100,
+          "r_filtered": 100
+        }
+      }
+    }
+  }
+}
+drop table t0, t1, t2;

mysql-test/r/explain_json.result

@@ -799,6 +799,7 @@ EXPLAIN
       {
         "query_block": {
           "select_id": 2,
+          "having_condition": "trigcond(<is_not_null_test>(t1.a))",
           "full-scan-on-null_key": {
             "table": {
               "table_name": "t1",
@@ -1110,3 +1111,86 @@ EXPLAIN
   }
 }
 DROP TABLE t1;
+#
+# MDEV-7970: EXPLAIN FORMAT=JSON does not print HAVING
+#
+create table t0(a int);
+insert into t0 values (0),(1),(2),(3);
+create table t1(a int);
+insert into t1 select A.a + B.a* 10 + C.a * 100 from t0 A, t0 B, t0 C;
+create table t2 (
+a int, 
+b int, 
+key (a)
+);
+insert into t2 select A.a*1000 + B.a, A.a*1000 + B.a from t0 A, t1 B;
+# normal HAVING
+explain format=json select a, max(b) as TOP from t2 group by a having TOP > a;
+EXPLAIN
+{
+  "query_block": {
+    "select_id": 1,
+    "having_condition": "(TOP > t2.a)",
+    "filesort": {
+      "temporary_table": {
+        "function": "buffer",
+        "table": {
+          "table_name": "t2",
+          "access_type": "ALL",
+          "rows": 256,
+          "filtered": 100
+        }
+      }
+    }
+  }
+}
+# HAVING is always TRUE (not printed)
+explain format=json select a, max(b) as TOP from t2 group by a having 1<>2;
+EXPLAIN
+{
+  "query_block": {
+    "select_id": 1,
+    "filesort": {
+      "temporary_table": {
+        "function": "buffer",
+        "table": {
+          "table_name": "t2",
+          "access_type": "ALL",
+          "rows": 256,
+          "filtered": 100
+        }
+      }
+    }
+  }
+}
+# HAVING is always FALSE (intercepted by message)
+explain format=json select a, max(b) as TOP from t2 group by a having 1=2;
+EXPLAIN
+{
+  "query_block": {
+    "select_id": 1,
+    "table": {
+      "message": "Impossible HAVING"
+    }
+  }
+}
+# HAVING is absent
+explain format=json select a, max(b) as TOP from t2 group by a;
+EXPLAIN
+{
+  "query_block": {
+    "select_id": 1,
+    "filesort": {
+      "temporary_table": {
+        "function": "buffer",
+        "table": {
+          "table_name": "t2",
+          "access_type": "ALL",
+          "rows": 256,
+          "filtered": 100
+        }
+      }
+    }
+  }
+}
+drop table t0, t1, t2;

mysql-test/t/analyze_format_json.test

@@ -150,3 +150,29 @@ analyze format=json (select * from t1 tbl1 where a<5) union (select * from t1 tb
 drop table t0, t1;
 
 
+--echo #
+--echo # MDEV-7970: EXPLAIN FORMAT=JSON does not print HAVING
+--echo #
+create table t0(a int);
+insert into t0 values (0),(1),(2),(3);
+create table t1(a int);
+insert into t1 select A.a + B.a* 10 + C.a * 100 from t0 A, t0 B, t0 C;
+create table t2 (
+  a int, 
+  b int, 
+  key (a)
+);
+insert into t2 select A.a*1000 + B.a, A.a*1000 + B.a from t0 A, t1 B;
+--echo # normal HAVING
+--replace_regex /"r_total_time_ms": [0-9]*[.]?[0-9]*/"r_total_time_ms": "REPLACED"/
+analyze format=json select a, max(b) as TOP from t2 group by a having TOP > a;
+--echo # HAVING is always TRUE (not printed)
+--replace_regex /"r_total_time_ms": [0-9]*[.]?[0-9]*/"r_total_time_ms": "REPLACED"/
+analyze format=json select a, max(b) as TOP from t2 group by a having 1<>2;
+--echo # HAVING is always FALSE (intercepted by message)
+--replace_regex /"r_total_time_ms": [0-9]*[.]?[0-9]*/"r_total_time_ms": "REPLACED"/
+analyze format=json select a, max(b) as TOP from t2 group by a having 1=2;
+--echo # HAVING is absent
+--replace_regex /"r_total_time_ms": [0-9]*[.]?[0-9]*/"r_total_time_ms": "REPLACED"/
+analyze format=json select a, max(b) as TOP from t2 group by a;
+drop table t0, t1, t2;

mysql-test/t/explain_json.test

@@ -278,7 +278,6 @@ explain format=json select count(distinct a1,a2,b,c) from t1 where (a2 >= 'b') a
 
 drop table t1;
 
-
 --echo #
 --echo # MDEV-8786 Wrong result for SELECT FORMAT=JSON * FROM t1 WHERE a=_latin1 0xDF
 --echo #
@@ -294,3 +293,26 @@ CREATE TABLE t1 (a VARCHAR(10) CHARACTER SET latin1);
 INSERT INTO t1 VALUES ('a'),('A');
 EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE NULLIF(a,_utf8'a' COLLATE utf8_bin);
 DROP TABLE t1;
+
+--echo #
+--echo # MDEV-7970: EXPLAIN FORMAT=JSON does not print HAVING
+--echo #
+create table t0(a int);
+insert into t0 values (0),(1),(2),(3);
+create table t1(a int);
+insert into t1 select A.a + B.a* 10 + C.a * 100 from t0 A, t0 B, t0 C;
+create table t2 (
+  a int, 
+  b int, 
+  key (a)
+);
+insert into t2 select A.a*1000 + B.a, A.a*1000 + B.a from t0 A, t1 B;
+--echo # normal HAVING
+explain format=json select a, max(b) as TOP from t2 group by a having TOP > a;
+--echo # HAVING is always TRUE (not printed)
+explain format=json select a, max(b) as TOP from t2 group by a having 1<>2;
+--echo # HAVING is always FALSE (intercepted by message)
+explain format=json select a, max(b) as TOP from t2 group by a having 1=2;
+--echo # HAVING is absent
+explain format=json select a, max(b) as TOP from t2 group by a;
+drop table t0, t1, t2;

sql/sql_explain.cc

@@ -862,6 +862,19 @@ void Explain_select::print_explain_json(Explain_query *query,
       writer->add_member("const_condition");
       write_item(writer, exec_const_cond);
     }
+    /* we do not print HAVING which always evaluates to TRUE */
+    if (having || (having_value == Item::COND_FALSE))
+    {
+      writer->add_member("having_condition");
+      if (likely(having))
+        write_item(writer, having);
+      else
+      {
+        /* Normally we should not go this branch, left just for safety */
+        DBUG_ASSERT(having_value == Item::COND_FALSE);
+        writer->add_str("0");
+      }
+    }
 
     Filesort_tracker *first_table_sort= NULL;
     bool first_table_sort_used= false;

sql/sql_explain.h

@@ -209,6 +209,7 @@ public:
   Explain_select(MEM_ROOT *root, bool is_analyze) : 
   Explain_basic_join(root),
     message(NULL),
+    having(NULL), having_value(Item::COND_UNDEF),
     using_temporary(false), using_filesort(false),
     time_tracker(is_analyze),
     ops_tracker(is_analyze)
@@ -232,6 +233,10 @@ public:
   /* Expensive constant condition */
   Item *exec_const_cond;
 
+  /* HAVING condition */
+  COND *having;
+  Item::cond_result having_value;
+
   /* Global join attributes. In tabular form, they are printed on the first row */
   bool using_temporary;
   bool using_filesort;

sql/sql_select.cc

@@ -24197,6 +24197,11 @@ int JOIN::save_explain_data_intern(Explain_query *output, bool need_tmp_table,
       xpl_sel->using_filesort= true;
 
     xpl_sel->exec_const_cond= exec_const_cond;
+    if (tmp_having)
+      xpl_sel->having= tmp_having;
+    else
+      xpl_sel->having= having;
+    xpl_sel->having_value= having_value;
 
     JOIN_TAB* const first_top_tab= join->first_breadth_first_optimization_tab();
     JOIN_TAB* prev_bush_root_tab= NULL;